What is it about?

A unique mariner's astrolabe decorated with iconic Portuguese markings was discovered in 2014 during archaeological excavations at the Sodré shipwreck site in Al Hallaniyah, Oman. Initially it was impossible to confirm the object as an astrolabe as no gradations were visibly apparent. However, 3-dimensional laser imaging of the object revealed a series of 18 regular scale marks on the limb that when digitally measured show they were graded at close to 5‐degree intervals. This evidence was used to independently confirm that the object was indeed a mariner's astrolabe and the earliest known example discovered to date.

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Why is it important?

This particular mariner's astrolabe is unique in a number of ways. Most importantly it is the only solid disk type mariner's astrolabe with a verifiable provenance and age. This makes us believe that it might be a transitional instrument in the development of mariner's astrolabes. Based on the known chronology of when the ship's left Lisbon for India, the likely date range for when it was made is 1496 to 1501, which makes it the earliest mariner's astrolabe found to date.


This astrolabe is a wonderful object that speaks directly to the ambition of the Portuguese king Dom Manuel as he set out to begin build an empire at the end of the 15th century. It was exciting and a great privilege to have found such a historically important object.

Mr David L Mearns
Blue Water Recoveries

Read the Original

This page is a summary of: An Early Portuguese Mariner's Astrolabe from the Sodré Wreck‐site, Al Hallaniyah, Oman, The International Journal of Nautical Archaeology, March 2019, Wiley, DOI: 10.1111/1095-9270.12353.
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